Organometallics 1985,4, 1208-1213
1208
a gift of RuC1, and Prof. H. Lehmkuhl for suggestions concerning NOE experiments. Registry No. 1,79681-92-8; l', 79732-92-6; 2a, 85153-18-0;2a', 85201-32-7;2b, 96151-62-1;2b', 96193-47-4;3, 88898-37-7;3', 88929-95-7; 4,90502-92-4; 4', 90581-29-6; (?-C5Hs)RuCl(chiraphos),
79681-91-7;(?-C,H,)RuH(chiraphos), 96151-63-2;CHDC12, 1665-01-6.
Supplementary Material Available: CD spectra of 2a and 2a' (Figure4),3 and 3' (Figure5),and 4 and 4' (Figure6)(3pages). Ordering information is given on any current masthead page.
Activation of Vinylidenebis(diphenyiphosphine) through Metal Complexation Hubert Schmidbaur, Rudolf Herr, Gerhard Muller,+ and Jurgen Riedet Anorganisch-chemisches Institut der Technischen UniversMt Miinchen, D 8046 arching, West Germany Received December 4, 1984
Vinylidenebis(dipheny1phosphine)(vdpp) was found to give an insoluble 1:2 complex, (vdpp)-(AuCl)z (l), but a soluble 1:l complex, (vdppAuCl)2 (2), when treated with (C0)AuCl in the appropriate molar ratio. The crystal structure determination of (~dppAuCl)~.CHCl, revealed a dimer with a centrosymmetric eight-membered ring skeleton composed of two P,P-bridging vdpp ligands, and trigonally coordinated Au(1) centers, with the two AuPzClplanes parallel to each other. The vinylidene groups are not engaged in metal bonding but have become strongly activated through the vdpp-metal coordination. Methanol is added at 20 "C to give the AuCl complex of l,l-bis(diphenylphosphino)-2-methoxyethane (6). This addition is reversible, and the CH30H is lost quantitatively at 150 "C, with recovery of 2. 1:l complexes were also prepared from CuC1, AgC1, AgOCOCH3,and AgBF4 (3,4a-c), but the vdpp ligands in none of these products is sufficiently activated to give similar addition reactions. Elemental analyses, osmometric molecular mass data, and 'H,13C,and 31PNMR, IR, and mass spectra were used for a preliminary characterization of the compounds. The X-ray data for 2 are as follows: (C,Hz2AuC1P2)zCHC13,a = 9.920 (2)A, b = 11,545 (2) A, c = 12.272 (2)A, a = 90.40 (l)', 0 = 88.25 (2)",y = 109.17 (l)",dcdcd = 1.723 g cm-3for 2 = 1, space group Pi;4339 observed reflections, R = 0.033,R, = 0.042.
Introduction A plethora of mono- or polydentate tertiary phosphines have been designed, synthesized, and introduced as ligands to metals and metal clusters in order to meet steric and electronic specifications suitable for application to stoichiometric or catalytic These ligand molecules may either be prepared independently and then be integrated into a coordination sphere or constructed in a template synthesis at the metal center(s). For the latter purpose, organophosphorus compounds with versatile functional groups are of prime importance. It is therefore surprising that in this context the potentially reactive phcsphino olefins have received little attention. Geminally phosphine-substituted olefins in particular are still rare species and have appeared in the literature only very re~ently.~+ In initial studies carried out in this laboratory it was found that the prototype molecule vinylidenebis(diphenylphosphine), for which convenient syntheses are a ~ a i l a b l e ,can ~ , ~be strongly activated by monoquaternization with an alkyl halide. In the absence of a suitable nucleophile, dimerization occurs to give cyclic semiylide salts in quantitative yield at room temperature.6 Double alkylation leads to bis(phosphonium) salts whose C=C bond is sufficiently electrophilic to add even weak components like alcohols, thiols, phosphines, or amines.610 A similar activation is induced by oxidation of the phosphines with oxygen or sulfur (Scheme I). These results made investigations highly desirable in which the effects of (ph0sphine)met.d complexation on the olefinic double bond is probed. A large variety of mono-
'X-ray structure analysis.
Scheme I
H C'
H 2x-
II
C Ph2P'
II z
'PPh*
II
z
2 x2 10,S. Se
or binuclear complexes are possible candidates as acceptor centers, and therefore almost any degree of activation could (1) Chatt, J.; Williams, A. A. J. Chem. SOC.1951, 3061. (2) McAuliffe, C. A.; Levason, W. "Phosphine, Arsine and Stibine Complexes of the Transition Metals"; Elsevier: Amsterdam, 1979. Levason, W.; McAuliffe, C. A. Coord. Chem. Reo. 1976,19, 173. McAuliffe, C. A. Adu. Inorg. Chem. Radiochem. 1975,17, 165. (3) Tolman, C. A. Chem. Reu. 1977, 77, 313. (4) Colquhoun, I. J.; McFarlane, W. J. Chem. SOC.,Dalton Trans. 1982, 1915. (5) Schmidbaur, H.; Herr, R.; Riede, J. Chem. Ber. 1984, 117, 2322. (6)Schmidbaur, H.; Herr, R.; Riede, J. Angew. Chem. 1984,96, 237; Angew. Chem., Znt. Ed. Engl. 1984,23, 247. (7) Schmidbaur,H.; Herr, R.; Pollok,T.; Schier, A.; Muller, G.; Riede, J. Chem. Ber., in press. (8) Weber, L. Universitiit Essen, private communication, 1984.
0276-7333/85/2304-1208$01.50/0 0 1985 American Chemical Society
Organometallics, Vol. 4, No. 7, 1985 1209
Activation of Vinylidenebis(dipheny1phosphine)
in principle be advanced. Shaw and collaborators could show in parallel and independent studies that a chelating 1,l-bis(phosphino)olefingenerated at a metal-carbonyl fragment indeed undergoes addition reactions with a number of substrates.lOJ1 Our own studies have also focused on binuclear complexes of a structure similar to that of the bis(dipheny1phosphino)methane (dppm) complexes,12-14whose chemistry is one of the most rapidly developing areas. Binuclear Vinylidenebis(dipheny1phosphine)Complexes of the Coinage Metals. Vinylidenebis(diphenylphosphine) (vdpp) reacts with carbonylcMorogold(1) in the molar ratio 1:2 in tetrahydrofuran with strong effervescence to give a colorless precipitate of the expected complex 1. This material is insoluble in all common organic solvents, including dimethyl sulfoxide, chloroform, or nitromethane. The molecular mass and structure could therefore not be determined, but a configuration similar to that of the dppm complex, which was determined by X-ray diffraction, should be valid.13 The same components when reacted in equimolar ratio gave again (with evolution of CO gas) a yellowish precipitate, which is soluble in a number of polar organic solvents and could be crystallized from chloroform. The yields of this 1:l complex 2 were virtually quantitative. The composition and structure could be elucidated by analytical, diffraction, and spectroscopic methods (below). The molecular structure closely resembles that of the dppm complex.', H
H L
Silver(1) chloride when treated similarly with vdpp in THF gave no well-defined products. There were no problems, however, when the reaction was carried out in methylene chloride. The off-white 1:l complex 4a is very soluble both in CH2C12or CHC1,. An analogous acetate 4b was also obtained in THF, and a tetrafluoroborate 4c was formed with AgBF, in the same solvent. All three compounds could be obtained as colorless airand light-stable crystalline solids in good yields. Their structures remain to be determined, but a few reference models with dppm are again already a ~ a i l a b l e . ' ~ ' ~ Like 3, the silver complexes 4a-c are soluble in chloroform. Molecular mass determinations by osmometry gave values slightly higher than those calculated for dimers of 4b,c and between those for dimers and trimers in the case of 4a, respectively (at 25 "C): calculatea for dimers 4a, 1079.5, 4b, 1126.6, and 4c, 1182.2; found (C = 0.01 M in chloroform) 4a, 1483,4b,1234,and 4c, 1266. It is therefore concluded that the chloroform solutions contain largely dimeric species in the form of discrete complexes or tight ion pairs (4c). The mass spectra of 4a (field desorption, 100 "C)gave only the ion of the vdpp ligand, probably due to low volatility of the oligomer. With 4b, a dinuclear fragment [(vdpp)Ag20Ac]+was observed as the parent ion ( m / e 670 (100%)) with correct isotopic ratios. 4c, under similar conditions, showed the [ (vdpp Ag)2]2+double cation, however, again with the correct isotopic ratio for the two silver ions lo7Agand lmAg in natural abundance. These results suggest, that in 4a or 4b the chloride or acetate anions, respectively, are strongly associated with the metal centers in the solid and in solutions, whereas the fluoroborate 4c is largely ionic in character. This is also borne out by the IR absorptions of 4b at 1560 (vs) and '1400 (vs) cm-' for coordinated acetate (v(C00)) and of 4c at 1075 (vs) and 782 (w)cm-l for uncomplexed BF,.
CUCl
c H'
H
H'
H\
2 C''
Ph2P'
!
I
I
4""---4" CI
'PPh2
AqCl
C(PPh2)Z *CUCII,
3
tCH2=C(PPh&
*AgCIl,
4a
AgococnL CCH2=
C(PPh2)2mAgOCOCH31,
4b PPh2
Ph2PL' '
/
I1 C
H
H
C
tCH2
CI
1
Copper(1) chloride was easily dissolved in a solution of equimolar quantities of vdpp in THF, and a colorless precipitate formed upon addition of hexane to the solution. The 1:l complex 3 is soluble in chloroform and methylene chloride. Structures of a few related dppm complexes of copper(1) halides have been described in the literature,15 and a similar skeletal buildup is to be anticipated for 3. (9)Schmidbaur, H.; Herr, R.; Muler, G. 2. Chem. 1984,24, 378. (10)Cooper, G.R.;McEwan, D. M.; Shaw, B. L. Znorg. Chim. Acta 1983,76,L165. (11)Al-Jibori, S.;Shaw, B. L. J. Chem. SOC., Chem. Commun. 1982, 286. Al-Jibori, S.;McDonald, W. S.; Shaw, B. L. J. Chem. SOC.,Chem. Commun. 1982,287. (12)Puddephatt, R. J. Chem. SOC.Rev. 1983,12,99. (13)Schmidbaur, H.; Wohlleben, A.; Wagner, F. E.; Orama, 0.; Huttner, G. Chem. Ber. 1977,110,1748. (14)Schmidbaur, H.; Wohlleben, A.; Schubert, U.; Frank, A.; Huttner, G. Chem. Ber. 1977,110,2751. (15)Nardin, G.;Wdaccio, L.;Zangrando, E. J.Chem. Soc., Dalton Trans. 1975,2566 and references therein.
3CCH2=
C(PPh2)2-Ag12*2BF4
4c
Complexes 2-4 show characteristic resonances in their
NMR spectra for the olefinic moiety, which clearly remains intact upon metal coordination at phosphorus. The vinylidene hydrogen atoms give rise to signals in the low-field olefin region very close to the resonances of the aryl hydr~genatoms. In fact in a few cases even overlap of signals occurs. Quite often vinylidene carbon resonances coincide similarly with phenyl carbon resonances (Table I). The observed spin systems provide evidence for a retained C2or m symmetry of the ligands in the complexes in solution. Thus the vinylidene protons give AA'XX' spectra in all cases, and the PCP carbon atoms appear as simple triplets or symmetrical signal groups if additional P-P couplings across or with the metal atoms (1°'Jo9Ag) (16)Aly, A. A. M.; Neugebauer, D.; Orama, 0.;Schubert, U.; Schmidbaur, H. Angew. Chem. 1978,90,125;Angew. Chem., Znt. Ed. Engl. 1978,17,125 and references therein. (17)Schubert, U.;Neugebauer, D.; Aly, A. A. M. Z. A n o g . Allg. Chem. 1980,464,217. (18)Teo, B.;Calabrese, J. C. Znorg. Chem. 1976,15,2467,2474. Schubert, U. Angew. Chem. 1978, (19)Schmidbaur, H.;Aly, A. A. p.; 90,905;Angew. Chem., Znt. Ed. Engl. 1978,17,846.
1210 Organometallics, Vol. 4, No. 7, 1985
Schmidbaur et al.
Table I. NMR Spectraa of Compounds 2,3,4a-c, and 6 2 3 4a 4b 4c CDC13 CDC13 CDCls CDCl,/CD,OD CDC13 6.4 6.3 6.25 (m) 6.26 6.7 7.2 6.8-7.5 7.25 7.55 7.0-7.75 1.73 (8) "
solvent b(CH2) (AA'X') b(C$I,) (m) b(CH3) WH) ~ ( C H Z(N) ) b ( c p z ) (4 b(CH3) b(C0Z) 6(C-1) (N) 6(C-2) (N) 6(C-3) (N) b(C-4) b ( P ) (N)
145.5 (s) 135.4 (t,43.9)
138.9 (5) 142.7 (mIb
139.4 (s) 141.8 (s)~
124.2 (60.6) 128.6 134.0 131.9 42.3 (s)
128.9 (m)' 128.0 133.3 129.8 -2.2 (9)
128.5 (m). 128.5e 1338 130.2e 10.5 (425)'
140.1 (s) 141.8 (s) 24.2 (8) 177.1 (8) 128.4 (m)' 128.4 133.8 130.8 14.7 (439.5)f
142.6 ("t", 7) 136.6 (26.4) 125.1 (50.8) 129.5 134.6 131.9 21.9 (534.1)f
6
CD30D 3.53 6.9-8.2 2.80 (s) 5.73 (br) 67.8 (br) 32.1 (br) 58.2 (9) 125.2 (58.6) 129.1 (2.9) 134.1 (3.9) 132.6 46.6 (s)
6' in ppm; J / N in Hz; 13Cand spectra were 'H decoupled. bVirtual septet structure. 'Obscured by other resonances. dlJ(CH) = 158 Hz. elJ(CH) = 163 i 1 Hz. funresolved 31P-*07/10aAg coupling.
occur. A detailed analysis was not carried out, as quite satisfactory treatments are already available for the dppm analogues.20 Contrary to the situation in the methanol adduct (below), the four phenyl groups of each ligand are equivalent and only one set of carbon-13 resonances is observed, not withstanding a complex multiplet structure of the signals due to virtual coupling through the phosphorus-phosphorus spin interaction. There is ample precedence for the resulting NMR patterns.21 The NMR spectra of 4a and 4b have almost identical signals for the vdpp ligands, but the spectrum of 4c is very different. It is therefore concluded that the first two have very similar structures, whereas the latter should be of another probably ionic type. Crystal and Molecular Structure of 2. Like the dppm analogue [CH2(PPh2)2AuC1]2, the vdpp complex is found to crystallize in the form of discrete dimers with crystallographically imposed centrosymmetry as shown in Figure 1. Each chlorine atom is attached to a gold atom at a distance of 2.723 (2) A. Together with the two not quite equidistant phosphorus atoms P1 and P2 (from two different vdpp ligands) this chlorine atom completes a distorted trigonally planar environment for each gold(1) center. (The sum of the valence angles at Au is 359.9'). The two gold atoms, which deviate only 0.03 A from their individual Cl-Pl-P2 planes, are 2.977 (1)A apart, a distance not uncommon for gold atoms spanned by small-bite difunctional ligand^.'^,^^ The Au-Au* vector is approximately perpendicular (96.9') to the coordination plane around each Au atom. The overall geometry of 2 may be described as an eight-membered (AU-P-C-P)~heterocycle with a short transannular Au-Au contact. In crystals of the free vdpp ligand the two Ph2P group are in a quasi E / Z conformation (A) not suitable for bridging or chelating coordination? In complex 2, however, the expected P-C bond rotation of the E-oriented PPh2 group has occurred (B)in order to allow formation of a relatively strain-free eight-membered ring. The P1-Au-
1-1 A
0
(20) Van der Ploeg, A.; Van Koten, G.Inorg. Chim. Acta 1981,51,225. (21) ,Redfield, D. A,; Nelson, J. H.; Cary, L.W.Inorg.Nucl. Chen. Lett. 1974, 10,127. (22) Jones, P. G. Gold Bulletin 1983,16, 114; 1981,14, 102 and 159.
Au*-P2 torsion angle in 2 amounts to only -24.9'. All other dimensions of the free vdpp ligand are largely unchanged in complex 2 with the exception of the P1-C1-P2 valence angle which is compressed from 119.0 (3)' to 115.8 (3)' upon complex formation. The latter value, however, is not much different from the corresponding P-C-P angle in the analogous dppm complex (114.2 (8)014). Also, the fact that all other geometrical features of both complexes are directly comparable indicates that the observed eight-membered ring geometry best suits the different stereochemical requirements of the constituent heavy atoms, whereas the relatively flexible bridging carbon atoms have to adjust themselves to these requirements. The C=C elongation (a possible evidence for C=C activation by P-Au coordination) does not exceed the standard error of the X-ray experiments. The sum of the valence angles at the inner olefinic carbon atom C1 is 359.6', clearly indicating a classical sp2state of bonding. It is this carbon atom, where the structurally diagnostic pyramidalization occurs with the addition of qethano17 (below). The Au-C1 distances in complex 2 (2.723 (2) A) are rather large and exceed slightly the standard values for Au' complexes.22They are still shorter, however, than in the analogous dppm complex:14 2.771 (4) A. A high ionic character is therefore ascribed to these Au-C1 bonds, as in the previous exam~1e.I~ For the dppm complex it could in fact be demonstrated that a fully ionic species can be easily generated with the tetraphenylborate anion instead of the chloride ~0unterion.I~ Reversible Methanol Addition to the Activated C = C Bond in Complex 2. The free vdpp ligand does not add weak nucleophiles under standard conditions," and only its quaternization or oxidation products exhibit a sufficiently activated C=C bond to allow such reactions (Scheme I). Coordination of gold atoms to both phosphorus centers has now been shown to have a similar effect. When compound 2 was dissolved in methanol at room temperature, an addition reaction was slowly taking place which was virtually complete after a few days. Colorless needles of product 6 could be isolated after partial evaporation of the solvent. The process can be followed by NMR spectroscopy. The 31Presonance is shifted by 4.3 ppm upon coordination, and the lH and 13Csignals of the vinylidene group are replaced by a set of resonances in the aliphatic region characteristic of a P2CH-CH2-OCH3group (see Experimental Section). Due to the structural features, the two CH h drogen atoms in 6 are anisochron~us~~ (J's are anisogamous y24 ), and (23) Schrumpf, G. J. Magn. Reson. 1972, 6, 243.
Organometallics, Vol. 4, No. 7, 1985 1211
Activation of Vinylidenebis(dipheny1phosphine)
the phenyl groups at each phosphorus atom are diastereotopic, but the effect is only noticable for the C1 signals. The overall pattern is very similar to that observed in the spectra of the phosphonium salt [(MePh2P)2CHCH20CH3]2+21in Scheme I (Y = OCH& The structure of this derivative has already been confiied by X-ray diffraction analysis.'
decomposition), insoluble in CHC13, CHBN02, and Me2S0. Anal. Calcd for CzsHzzAuzClZPz (861.25): C, 36.25;H, 2.57; Au, 45.74. Found C, 36.22; H, 2.75;Au, 45.20.
Bis[p-vinylidenebis(diphenylphosphine)]dichlorodigold(I) (2). A 1.96-g sample of Au(C0)Cl (7.52mmol) was treated with a solution of 3.00 g of vdpp (7.53mmol) in 40 mL of THF at -70 "C. CO gas was evolved and a white precipitate formed, which was filtered after warming to room temperature, washed with THF, and dried in vacuo. The product can be crystallized from CHC13/CH30H. Pale yellow crystals are obtained yield 4.17 g (88.2%); mp 206 O C (with decomposition). Anal. Calcd for C62HllA~ZC~ZP4 (1257.66): C, 49.66;H, 3.52; Au, 31.32;C1, 5.63. Found: C, 49.42;H, 3.52;Au, 31.90;C1,5.60.
[Vinylidenebis(diphenylphosphine)]chlorocopper(I) (3) and [Vinylidenebi~(diphenylphosphine)]chlorosilver(I), - (acetato)silver(I), and - (tetrafluoroborato)silver(I) (4a-c). A 1.19-gsample of CuCl (12.02 mmol) was treated with 4.77 g in 60 mL of T H F at room temperature for of vdpp (12.02"01) CHg CH2 2 h. From the resulting clear solution the product could be 2 cyo' precipitated by careful addition of 20 mL of hexane. The colorless solid 3 was filtered and dried in vacuo: yield 5.22g (43.8%); mp 6 235 O C (with decomposition). Anal. Calcd for C62H4c12Cu2P4(990.81): c , 63.03;H, 4.47; In a thermogravimetric analysis compound 6 was found C1, 7.15; Cu, 12.82. Found: C, 62.12;H, 4.51;C1, 7.33;Cu, 13.01. to loose ita methanol quantitatively at 150 "C. The yellow Compound 4a was prepared from 0.26 g of AgCl (18.2mmol) parent compound is restored at this temperature without and 0.72 g of vdpp (18.2 mmol) in 30 mL of CHzClz at reflux any sign of decomposition. The identity of regenerated temperature (20min). After evaporation of the solvent, a pale 2 was checked by NMR spectroscopy and analytical data. yellow product remained in quantitative yield (0.98g, 100%); mp The above reaction is thus fully reversible. This is an 133 "C. important observation which demonstrates that ligand (1079.46):C, 57.86;H, 4.11. Anal. Calcd for C62HuAg2C12P4 activation through complex formation is possible but not Found: C, 57.65;H, 4.02. necessarily irreversible. It is hoped that work in progress Compound 4b was formed when 4.04 g of vdpp (10.2mmol) and 1.63 g of AgOCOCH, (9.78mmol) were dissolved in 40 mL with other complexes and substrates will shed further light of THF. After a few minutes a colorless precipitate of the product on the scope of this reaction. In parallel studies the acappeared, which was filtered and dried in vacuo: yield 3.45 g tivation of the cyclopropane ring in cyclopropylidenebis(diorganophosphines) (C) is currently investigated.'~~~ (52.6%), mp 172 "C (with decomposition). Anal. Calcd for CS6H&g204P4 (1126.65): C, 59.69;HI 4.47; Difficulties in the preparation of suitable allene systems Ag, 19.14. Found: C, 59.57;H, 4.55; Ag, 19.00. D have limited their study to only a few exploratory exCompound 4c was prepared as described for 4b from 2.00 g periments.26 of AgBFl (10.3 mmol) and 4.11 g of vdpp (10.3mmol) in 50 mL of THF. The product can be recrystallized from CHCl,: colorless plates; yield 4.43 g (73.04%); mp 245 "C (with decomposition). Anal. Calcd for C62H4rlAg2B2F$4 (1182.17): C, 52.83;H, 3.75; Ag, 18.24; F, 12.85. Found C, 52.54; H, 3.69;Ag, 18.13;F, 13.16. I1 c Bis[p-l-methoxy-2,2-bis(diphenylphosphino)ethane-P,/ \ HC\ /c\ PQ'Qldichlorodigold(1) (6). A 2.27-g sample of compound R2P PR2 R2P PR2 R2P PRz 2 (1.80mmol) was dissolved in methanol. After 2 days at room , I
C
A. B
D
Surprisingly, in none of the copper and silver complexes 3 and 4a-c is the vdpp ligand sufficiently activated to give similar addition reactions under standard conditions. Clearly, specific effects are necessary, which still need to be defined in future investigations.
Experimental Section All experiments were carried out under an atmosphere of dry purified nitrogen. Glassware and solvents were treated accordingly. Vinylidenebis(dipheny1phosphine)(vdpp) was prepared following a published procedure.6 CuC1, AgC1, AgBF4, and AgOCOCH, either are commercially available or are easily prepared by using standard methods. Au(C0)Cl was obtained via Calderazzo's synthesis.% [Vinylidenebis(diphenylphosphine)]chlorogold(I) (1). A 3.97-g sample of Au(C0)Cl (15.24 mmol) was treated with a in 40 mL of tetrahydrofuran solution of 3.02 g of vdpp (7.62"01) at -60 "C. CO was evolved and a white precipitate formed, which was filtered after being warmed to room temperature, washed with THF, and dried in vacuo: yield 5.72 g (87.1%); mp 265 "C (with (24) Radcliffe, M. D.; Mislow, K. J. Org. Chem. 1984, 49, 2058. (25) Schmidbaur, H.; Pollok, T. HeEu. Chim. Acta 1984,67,2175 and
unpublished results. (26)
1099.
Dell'Amico, D. B.; Calderazzo, F. Carr. Chim. Ztal. 1973,
103,
temperature the solvent was allowed to evaporate slowly. After 10 days colorless needles had formed, which were coMected and dried in vacuo, yield 1.59 g (67%); elimination of CH30H at 146-150 "C with formation of compound 2. Anal. Calcd for CS4H62A~2C1202P4 (1321.75): C, 49.07;H, 3.96; Au, 29.80. Found: C, 48.33;H, 3.90; Au, 30.30.
X-ray Structure Determination of Bis[p-vinylidenebis(diphenylphosphine)]dichlorodigold(I) (2). Crystal data: CzsHnAuCIP .0.5CHC13, M, = 688.522,triclinic, space group Pi, a = 9.920 (2) b = 11.545 (2)A, c = 12.272 (2)A, a = 90.40 (l)", 0= 88.25 (2)",y = 109.17 (l)", V = 1326.91A3,dd = 1.723 g/cm3 for Z = 2,F(000)= 666,T I= -35 "C.
h,
Suitable single crystals of 2CHC1, were grown from CHC13and sealed under an atmosphere of argon in a Lindemann glass capillary. According to diffractometer measurements (Syntex P2,) it crystallizes triclinicly. No higher symmetry was indicated by reduced cell calculations (TRACER). The exact cell dimensions and their esd's were obtained by a least-squares fit of the parameters of the orientation matrix to the setting angles of 15 high-order reflections from various parts of reciprocal space accurately centered on the diffractometer. Intensity data: One form of data (h = 0 - (ll),k = 0 - (&13), 1 = 0 - (&14); 1 I 0 5 25.0") was measured on a computer-controlled four-circle diffractometer equipped with a graphite monochromator and a scintillation counter. A multispeed moving crystalatationary counter technique was employed where the peak height at the calculated peak position served to determine the final scan speed (w scan, Aw = lo, 0.9 I d I 29.3"/min; Mo K a radiation, h = 0.71069 A). The time spent measuring the back-
1212 Organometallics, Vol. 4, No. 7, 1985
Schmidbaur e t al. Table 11. Fractional Atomic Coordinates and Equivalent Isotropic Thermal Parameters for 2a
(32
Au
c1
P1 P2
c1
Figure 1. ORTEP representation of the molecular structure of 2 with atom numbering scheme used (thermal ellipsoids at the 50% probability level). The atoms with an asterisk are related to the ones without an asterisk by a center of inversion. ground intensities at each end of the scan interval was half that taken to measure the peak. A monitor reflection ( l l l ) , measured after every 50 reflections, served as a check on the centering and stability of the crystal and diffractometer system. There was no significant change in its intensity variation. The intensity of a reflection and its standard deviation were calculated as Z = ( S - B/j3)b and a Q = (S - B/p2)1/2b,where S is the totalscan counts, B the total background counts, and fi the time ratio of total background to scan. The intensity data were corrected empirically for absorption by recording scans at 10' intervals around the diffraction vectors of eight selected reflections (p(MoKa) = 59.1 cm-'; Syntex XTL). After Lorentz and polarization corrections (F,= ( I / L P ) * /a(FJ ~ , = u(n/(2Fd;p))4339 structure factors with F, 1 4.0a(F0) out of a total of 4658 were considered statistically significant and used in all further calculations. Structure solution and refinements: The gold atom position could be deduced from a Patterson synthesis. Subsequent Fourier syntheses revealed the remainder of the molecule. After anisotropic refinement of the non-hydrogen atoms, 13 of the 22 hydrogen atoms, including those at the ethylene part of the ligand, could be located in difference maps. The rest was calculated a t idealized geometrical positions (d(C-H) = 0.975 A). The strongest peaks, belonging to a highly disordered chloroform molecule located near an inversion center, were fitted to idealized geometry and refined as rigid body with half occupancy and individual isotropic temperature factors. A total of 281 parameters were refined by full-matrix least s uares to R = C(IIFol- lFcll)/CIFol = 0.33, R, = [Cw(lF,I - IFJ)/CWF:]'/~ = 0.042, w = k / 0 2 ( F o ) , and k = 2.0 in the last cycle (non-hydrogen atoms anisotropic and hydrogen atoms constant, SHELX 76). The function minimized was Ew(lFol - lFc1)2.In the final refinement cycle the maximum shift to error ratio of parameters belonging to the complex were smaller than 0.1, whereas those of the solvent were only partially convergent. A final difference map showed peaks between 0.86 and 2.49 e/Aa near the solvent molecule; the highest peaks near the Au atom position had heights between 0.47 and 0.76 e/A3; all other peaks were equally distributed throughout the cell. Scattering factors for neutral, isolated, non-hydrogen atoms were taken from Cromer and Wabefl and those of the hydrogen atoms, based on a bonded spherical atom model, from Stewart, Davidson, and Simpson.28 Corrections for Af' and Af" were applied for all atoms.2B Table I1 lists the final atomic coordinates and
9
c2 c3 C31 C32 c33 c34 c35 c4 C41 C42 c43 c44 c45 c5 C51 C52 c53 c54 c55 C6 C61 C62 C63 C64 C65 Cool ClOl c102 C103
0.3512 (0) 0.4198 (2) 0.3906 (2) 0.7169 (2) 0.5677 (6) 0.5869 (6) 0.2716 (6) 0.2294 (6) 0.1444 (8) 0.1006 (8) 0.1418 (8) 0.2264 (6) 0.3838 (6) 0.3014 (8) 0.2853 (9) 0.3567 (9) 0.4398 (9) 0.4545 (8) 0.8431 (6) 0.9839 (6) 1.0802 (6) 1.0356 (8) 0.8941 (8) 0.7982 (6) 0.8032 (6) 0.8627 (6) 0.9378 (8) 0.9487 (6) 0.8866 (8) 0.8154 (6) 0.4704 (11) 0.4725 (11) 0.3332 (11) 0.6388 (11)
0.4861 (0) 0.6991 (1) 0.3714 (1) 0.4847 (1) 0.4446 (5) 0.4789 (6) 0.3526 (6) 0.2491 (6) 0.2422 (6) 0.3396 (9) 0.4447 (8) 0.4532 (6) 0.2186 (5) 0.1647 (6) 0.0437 (6) -0.0205 (6) 0.0329 (6) 0.1517 (6) 0.6242 (6) 0.6348 (6) 0.7472 (6) 0.8481 (6) 0.8366 (6) 0.7272 (6) 0.3688 (6) 0.3362 (6) 0.2525 (6) 0.2010 (6) 0.2316 (6) 0.3172 (6) 0.8592 (9) 0.7264 (9) 0.9122 (9) 0.9760 (9)
0.0369 (0) 0.1519 (1) 0.1809 (1) 0.1357 (1) 0.2357 (5) 0.3390 (5) 0.2998 (5) 0.3639 (6) 0.4564 (6) 0.4866 (6) 0.4225 (6) 0.3294 (6) 0.1423 (5) 0.0543 (6) 0.0243 (6) 0.0803 (6) 0.1670 (8) 0.1983 (6) 0.1898 (5) 0.2087 (5) 0.2395 (6) 0.2523 (6) 0.2342 (6) 0.2034 (5) 0.1477 (5) 0.0553 (5) 0.0606 (6) 0.1596 (6) 0.2525 (6) 0.2480 (6) 0.3920 (8) 0.4622 (8) 0.4448 (8) 0.3953 (8)
0.020 0.033 0.020 0.021 0.021 0.031 0.025 0.032 0.038 0.039 0.040 0.032 0.023 0.032 0.041 0.040 0.039 0.035 0.024 0.028 0.034 0.037 0.038 0.031 0.023 0.029 0.036 0.033 0.033 0.032 0.106 0.164 0.226 0.265
a U,, = (U1U2U3)1/3, where U,, U,, and U3are eigenvalues of the Uijmatrix. Esd's are in parentheses.
Table 111. Selected Interatomic Distances (A) and Angles (deg) of 2 with Esd's in Units of the Last Significant Figure in Parentheses Au-Au* Au-Cl P1-Au P~-Au* P1-c1 P2-c1 P 1-Au-Cl P2*-Au-C1 P l-Au-P2* Au*-Au-Pl Au*-Au-P2 Au*-Au-Cl Pl-Cl-P2 P1-c1-c2
Bond Distances C1-C2 2.977 (1) 2.123 (2) Pl-C3 2.333 (1) Pl-C4 P2-C5 2.302 (1) 1.828 (6) P2-C6 1.833 (6) Bond Angles 94.3 (1) P2-Cl-C2 110.4 (1) Au-P1-C1 155.2 (2) Au-PL-C~ 85.8 (1) Au-Pl-C4 93.3 (1) Au*-P2-C1 95.7 (7) Au*-P2-C5 115.8 (3) Aur-P2-C6 122.5 (5)
1.326 (9) 1.817 (6) 1.804 (6) 1.820 (6) 1.818 (6)
121.3 (5) 110.7 (2) 116.5 (2) 113.5 (2) 112.8 (2) 111.9 (2) 115.6 (2)
equivalent isotropic temperature factors of the non-hydrogen atoms; Table I11 contains important bond lengths and angles. Figure 1gives an ORTEP representation of the molecular structure.
Acknowledgment. This work has been supported by Deutsche Forschungsgemeinschft, Bonn-Bad Godesberg, by Fonds der Chemischen Industrie, Frankfurt/Main, and by Hoechst AG, Koln-Knapsack, and Degussa AG, Hanau. We thank Dr. F. R. Kreissl for the mass spectra and the staff of the microanalytical laboratory for the analytical data.
(27) Cromer, D. T.; Waber, J. T. Acta. Crystallogr. 1965, 18, 104. (28) Stewart,R. F.; Davidson, E. R.; Simpson, W. T. J. Chem. Phys. 1965,42, 3175.
( 2 9 ) "International Tables for X-RayCrystallography"; Kynoch Press, Birmingham, England, 1974; Vol. IV.
Organometallics 1985,4, 1213-1218 Registry No. 1, 96452-99-2; 2, 96453-00-8; 2-0.5CHC13, 96453-01-9; 3, 96453-02-0; 4a, 96453-03-1; 4b, 96453-04-2; 4c, 96453-06-4;6,96453-07-5;vdpp, 8449489-3;Au(CO)Cl,50960-82-2; CuCl, 7758-89-6;AgCl, 7783-90-6;AgOCOCH,, 563-63-3;AgBF,, 14104-20-2.
1213
Supplementary Material Available: Additional crystal structure data and tables of final anisotropic thermal parameters, H atom parameters, and observed and calculated structure factors (26pages). Ordering information is given on any current masthead page.
Synthesis of Optically Active Allyltin Compounds and Their Application to Enantioselective Synthesis of Secondary Homoallyl Alcohols Junzo Otera, Yukari Yoshinaga, Takeshi Yamaji, Takakazu Yoshioka, and Yuzuru Kawasaki Okayama University of Science, RMakho, Okayama 700, Japan Received September 14, 1984
Three types of optically active allyltin compounds, R*2Sn(allyl)2(R* = 2-phenylbutyl, 2-methylbutyl, and 3-phenylbutyl), R*R'Sn(allyl)2 (R* = 2-octyl or 2-phenylbutyl, R' = phenyl), and R*R1R2Sn(allyl) (R* = 2-phenylbutyl,R' = phenyl, R2 = methyl), have been synthesized. On the basis of 'H NMR spectra, a *-stacking interaction between the 2-phenylbutyland the allyl groups is suggested. Optically active allyltin compounds thus obtained were subjected to reaction with aldehydes. Among various allyltin compounds, only diallylbis(2-pheny1butyl)tinexhibits good enantioselectivity. The reaction proceeds through addition of the allyl group on the re face of aldehydes. The mechanism can be accounted for on the basis of a *-stacking interaction between allyl and phenyl groups.
Introduction Enantioselective synthesis of secondary homoallyl alcohols from aldehydes and optically active allylmetal compounds has received much attention recently. As templates for chirality transfer, there have appeared three types of organometallics. One of them is based on utilization of an optically active allylic group. Hayashi et al.l have synthesized a-substituted allylsilanes in which silicon is directly bonded to an asymmetric a-carbon. These compounds, on treatment with aldehydes, afforded secondary homoallyl alcohols of up to 90% ee. More recently, (adkoxycroty1)tin derivatives have been found to react stereoselectively with benzaldehyde.2 Employment of a chiral metallic center is the next choice. Unfortunately, however, Paquette et al. have found the reaction of (-)a-naphthylphenylmethylallyhilanewith acetals to give rise to unsatisfactory enantiomeric excess (
